The LED printhead consists of several thousand individual LED's. Due to the inherent variation in LED response, the light output varies from LED to LED within the same printhead for the same amount of energizing current. This results in a non-uniform exposure of an otherwise uniform field. This non-uniformity must be corrected in order to produce acceptable images in electrophotographic systems that employ these printheads as exposing devices. In the prior art, this non-uniformity has been corrected by consolidating all the numerous individual LED on-times into a few (e.g., 256) in such a way that the maximum exposure deviation from the average is minimized for each grey level. The approach as set forth in my U.S. Pat. No. 5,666,150, the pertinent content of which are incorporated herein by reference, results in good uniformity required to produce medium-to-high quality images. The limitation of this approach is that it is concerned only with minimizing the maximum exposure deviation from its average without attempting to optimize the distribution of all the intervening exposures. In order to produce the uniformity that is needed for very high quality images, I have determined that it is necessary to optimize the distribution of all exposures (at least for certain critical grey levels) in such a way that enhances the signal-to-noise ratio (snr) for those grey levels. This will be in addition to minimizing the maximum exposure deviation as noted in my patent.